Influence of characterised natural organic material on activated carbon adsorption: II. Effect on pore volume distribution and adsorption of 2-methylisoborneol

The adsorption of four ultrafiltration fractions of natural organic material (NOM) had a significant effect on the surface area and pore volume distributions of a coal-based activated carbon. This effect was dependent on the size of the compounds; the smaller fraction had the greatest effect on the micropore volume, and the larger fractions had a greater effect on the mesopore volume. Only the mesopore volume of a wood-based activated carbon was reduced by adsorption of the NOM fractions. The competitive adsorption between five NOM ultrafiltration fractions and 2-methylisoborneol (MIB) was greatest for the smallest fraction (ultrafiltration molecular weight <500), as this fraction was the most similar in size to MIB and therefore provided direct competition for the same adsorption sites. The NOM in a natural water sample displayed the greatest competition with MIB, due to the presence of small compounds that were lost during the concentration and desalting procedures used to obtain the NOM fractions. The competition between MIB and the largest ultrafiltration fraction was very small and could probably be attributed to smaller compounds present in this fraction.